Selective telephone system



Aug. 28, 1928. 1,682,068

J. F. cAvANAGH SELECTIVE TELEPHONE SYSTEM Filed Nov. 24, 1924' 2 Sheets-Sheet 1 gwuenloz ,28 JO/lh m/anagbf fluor "aus v J. F. CAVANAGH SELECTIVE TELEPHONE SYSTEM Filed Nov. 24, 1924 2 Sheets-Sheet 2 dfim.

INVENTOR J o1 E C' avana BY A TTORNEYS mAwNmk Patented Aug. 28, 1928.

UNITED STATES l,682,068 PATENT OFFICE.

JOHN F. CAVANAGH, OE PROVIDENCE, RHODE ISLAND, ASSIGNOB, TO THE SCR-Ew JNIACHINE PRODUCTS CORPORATION, OF PROVIDENCE, RHODE ISLAND, A COR- ronafrron or RHODE ISLAND.

SELECTIVE TELEPHONE SYSTEM.

Application ied November 24, 1924. Serial No. 751.824.

This invention relates to improvements in selective telephone systems, and has 'for its object' to provide means interposed in the circuit of such a system for controlling the connection between the calling and the selected or called station.

Ar further object of this invention'is to provide such a system in which the functions of both a selective signalling' and a central control systems are combined.

A still further object ot' this invention is to interpose in the signal circuit a central station having' a control element, whereby the central station must be called before connection can be completed to the selected station, and whereby the controlling element may be operated to permit a selected station to be called directly from the calling station.

This invention further consists in the provision of a unit adapted to be interpo ed in a selective signal circuit to permit one ot' the stations ot' the selective systems to serve as a central controlA station when desired.

The invention further consists inso con- Structing this central control unit that it may be readily attached to a telephone set.

Vith these and other objects in view, the invention consists ot' certain novel features of construction, as will be more fully described, and particularly pointed out in the appended claims.

In the accompanying drawings:

Figure l is a perspective view of a telephone desl; instrument having a selecting dial and a central control unit.

Figure 2 is a perspective view showing a iragmental portionoi the detachable hase of the desk instrument, illustrating the central control unit as mounted therein with a manually-operable contact closing member.

Figure 3 is a sectional elevation illustrating my improved central control unit as attached to the base of the usual desk instrument. I

Figure is a plan view ot my central Controlling in it as removed from the base oit the desir instr ment.

Figure 5 is a side elevation ot the contactclosing button member disconnected troni its "ra-megand showingl it rotated into retracted position.

nre G is the same as Figure 5 hut illustra. the button nieinher as rotated into e2:- tended position.

Figure 7 is a sectional elevation of tbe contact-closing button member, illustrating the geperal construction otl the same.

Figure S is a schematic diagram illustratmgthe wiringl connections to the different stations and instruments ot my improved selective telephone system.

In the practical operation of private telephone systems such tor instance as those em` aloyed in schools, hospitals, and various private institutions, it is found of advantage to provide means whereby control ot the use of the system between stations, may be exercised oy some person in authority, and in the absence or' such person the system may, if desired, be caused to function as a selective systeintor any desired period at which time anv station may call any other station without an acton the part of the operator at the central station.

Another advantageous feature of my improved telephoning system is that the central control station operator is no-t called upon to do the signalling for the calling partv but merely has to sanction the call by closing a relay to make a. connection, whereupon the one calling may signal directly to the called station thus requiring the exoen diture of but the minimum amount ot time by the central operator. rThen again by my improved system thecentral control circuit when temporarily set is automatically7 restored to its original condition at the end ot each talking period; and the following is a detailed description ot the present en'ibodiment of my invention showing one system of wiring and arrangement of parts by which these advantageous results maybe accomplished This invention, as herein described, is applied to an automatic telephone system of the common talking type having a multiplicity of telephone stations, and Figure 8 of the drawings illustrates the wiring diagram of three ot such stations indicated as stations l, 2, and 3. T he wiring diagrams of stations 2 and 3 illustrate the circuit connections to a telephone station ot the ordinary type, each of which has a rotatable dial by which one of the other dii'iferent stations in the system may be connected and signalled, while station l of my improved system is similarly wired and in addition, is provided with a central control unit l0 ot the type liest illustrated in Figares 2, 3, and et. The mechanism of the Celltral control unit is shown as mounted upon a base plate 1l which is provided with an annular flange 12 adapted to set inside of the lower rolled edge 13 of the base 14 of a portable desk instrumentl 15 and is adapted to be secured in position on the base ot the instrument by means ot a screw 16 threaded into the post 17.

On the base plate 11 are ymounted flexible spring contacts 22 commonly known in the trade as a build up which contacts are connected to the usual selecting switchboard or selecting unit by means ot wires 23 and V25 through binding screws 24. 'lhese spring contact members, as illustrated in Figure 8, are arranged to normally cause the pair ot contacts 107 to be separated to interrupt the ringing circuit between the selecting' and the selected stations and the pair ot contacts 101 to be in engagement to connect the ringing circuit ot the selecting station with that ot the central station. ln order that the ringing circuit to the selected station may be closed and that to the central station opened by an operator at the central station sanctioning the call an armature 19 having an arm 21 is pivoted at 2O on the yoke 26, which is supported on a bracket 27 fastened to the base plate 11, and is operated by push button 29 through a yielding presser member 31. rlhis button is slidably mounted in a tubular member 28 threaded into the flange 12 of the base memberpand normally held in withdrawn position by spring 32 acting between the button 29 and the bridge member 31a. An inward pressure on the button 29 serves to swing the armature 19 with its arm 21 to move contacts 107, see Figure 8, into engagenient and at the same time separate the pair of contacts 58 andthe pair oit' contacts 101, and in order to retain these contacts in this position to which they have been moved during the talking period an electromagnet 18 is provided which is energized upon movement ol these contacts to hold armature 19 in its operating position, thus it is only necessary for the central operator when desiring to sanction the call, to press the button 29 to connect the ringing circuit ot the calling station with that ot of the selected station, which connection is automatically maintained by this magnet 18 until all the ear phones in the circuit are placed in inoperative position en their respective hooks thus shutting oil the current flowing thru the lines. However, when the central operator desires to be temporarily absent the circuit .may be returned to selective service by causing the armature 19 to remain in call-sanctioned position. This is done by merely turningthe button 29 to the right which causes the pin 33 in the end 30 of the button 29 to ride'on the tace of the lcam 34 formed on the end ot the tubular member 28 and advance the pressed member 31 into engagement with the armature 19, the pin entering a recess 35, see Figure 6, in the edge of the cam which causes it to remain in this position thus connecting the circuit of the stations to operate as a selective service for a prolonged period, or until the button 29 is manually moved to withdrawn position.

lVith reference to the wiring diagram of Figure 8, in the operation of calling from station 2 to station 3 the dial 36 at station 2 (now the calling station), is rotated into position so that the designation corresponding to station 3 is under the pointer 46. The receiver 37 is then removed from its hook 38, which act opens hook switch contacts 39 and closes hook switch contacts 40, which closing completes the circuit to the connecting magnet. 41 drawing up armature 42, causing detent pawl 43 to move into operating relationship with the rack segment 44 against action otl spring 45. The electrical circuit which causes the action of this mechanism may be traced 'from battery 47 through wires 48 and 49 to contact points 40, through transmitter 50. induction coil primary 51, wire 52 to terminal 53, wire 54, through relay 55, wires 56 and 57 through central control contacts 58, wire 59, j ack 60, wire 61, connecting magnet 41. wire 62, jack 63, wire 64 to battery 47 Through the act ot lifting the receiver 37 the dial mechanism. is mechanically released which in returning `to normal, intermittently closes the contacts 65 a number ot times corresponding to the number ot the station sciected. which in this case is station 3. rtherefore. the necessary number oit impulses wil be transmitted to the selecting magnet 66 to cause the armature 67 to be operated the required number of times to rotate the wiper arm 68 step by step, to engage the contact designated as 3, which position of the wiper arm 68 is indicated by dotted lines. These transmitted impulses to the magnet 66 from contacts 65 may be traced on the wiring diagram o't Figure 8 as follows: From the plus side ot battery 47 through wires 48 and 49, through hook switch contacts 40, wire 69` vjack 70, interrupter contacts 65, jack 71, wires 72 and 73 to terminal 74. wire 75 through contacts 76 which were closed by armature 77 when the relay 55 was energized through the actot littingthe receiver from its hook, thence through wires 78 and 7 9, jack 80, wire 81, selecting magnet 66 back through wire 82, jack 63, wire 64 tothe minus side oi:n battery 47.

Assuming that the-central control conta cts and relay are in the position shown in Figure 8v`v the next act` at Vthe calling station is to press the push button 83 in the base of the instrument thus ringing a. bell 84 at station 1, which is herein shown as being connected to perform the function of Central Control station. The operation of pressing this button 83 shunts the primary of the induction coil at the calling station, in this case station Q, to. increase the current flow through connecting magnet 41 which dra vs up auxiliary armature 8G to close contacts 85 which completes the. circuit to bell 84. The ringing circuit may be traced on the wiring diagram of Figure 8 from the plus side ol battery 47 through wires 48, and L19, contacts 40, wire 69, jack 7 0, contacts 87, wire 88, jack 89, button co1 acts` 90, Wires 91 and 92, terminal 53, wire 54, through relay to wire 56 downthrough wire 57 contacts 58, wire 59, jaclt 60, wire 61, connecting magnet d1 which draws up armature 86 to close contacts 85, haelt through wire 62, through jack 63, wire G4, to the minus side ot' battery 47. The closing ot contacts shunts the current to hell 84, which may he traced in the following manner :-Taling the current 'from wire 56, pre iiously traced and shown to he conducting current upon the pushing oft' button 8,3, it is conducted through relay 93, Wire 94 to terminal 95 through hell 84, wire 96, hook switch contacts 97, wire 98, terminal 99, wire 100, through contacts101, wire 102, jack 103, Wire 104,-, contacts 85, wires 105 and 81, through selecting magnet 66, wire 82, jack 63, wire 64 hack to the minus side of battery 4:7.

It will he seen that instead of ringing the hell ot the selected station directly (here station 3) the central station is notified hy the ringing of its bell. It now central station sanctions the call, button 29 of central control unit is pushed inwardly, and as current is flowing through wires 56, and 57, contacts 58 and wire 59, the opening of contacts 58 hy the pushing of button 29 shunts the current along 7ire 105, through magnet 10, wire 106, hack to wire 59 energizing magnet- 10 to hold armature 19 in operating position. The drawing up ot the armature separates the contacts at 58 and at 101 and closes contacts 107. The calling station #2 may now signal the called station #-3, directly. In other words, th

ringing circuit of station 2 is directly connected to the ringing circuit of station 3, whereby now the hell 108 may be rung by operating push hutton 83, which circuit is traced on the wiring diagram as follows: The pressing of the button closes contacts 85 as pointed out above and the current ot the circuit thus completed is traced by taking the current received from wire 56 which passes through relay 109, wire 110, terminal 111, bell 108 through hook s itch contacts 112 haclrto wire 113, terminal 114, wire 115, to #3 contact point of the selector through wiper arm 68, brush 116, wire 117, jack 118, wire 119, central control unit contacts 107,'wirc 102,- jacl 108, contacts 85, wire 81, selecting mag-y nets 66, Wire 82, ack 63, wire (is to the minus side of battery 47, This circuit energized by the pressing et button 83 serves to ring the.

bell 108 of station 3, which ringing calls that station after which the conversation between these two stations may take place. Upon the completing of which conversation and the hanging up oit the receivers upon their respective hooks, the connecting magnet li1 is deenergized and the retaining pawl d3 is caused to release its segment permitting it to return to normal under action of spring 45 and open the circuit to all o the stations and at the same time magnet 10 is decnergized releasing armature 19 and restoring its contact points to normal.

From the above it will he seen, that a ringing circuit to a selected station is completed only when the armature 19 is pressed downwardly against the magnet 10, and when the opera-tor desires to leave the central station for a prolonged stay it is only necessary to rotate the presser' button 29 which loclrs the armature 19 in operative position thus permitting the calls` from any station to pass direct-ly to the called station independently of any action at the central station.

ythe foregoing description is directed solely towards the construction illustrated, but I desire it to he understood that I reserve the privilege ot resorting to all the mechanical c to which the device is susceptible, the invention heing defined and limited only by the ter .is ot the. appended claims.

I claim:

1. In a selective telephone system, a plurality of stations, means for connecting said stations in circuit, an automatic selecting swi tchhoard for partially completing the connection between said stations, controlling means interposed in said connecting means at one of said stations tor connecting that station to he called before the connection between any two other s'ations can he completed,'an`d manually operable means 'for completing the connection between said two other stations.

2. In a selective telephone system, a plu- `ality of stations, means for connecting said stations in circuit including a signal circuit, an automatic selecting switchhoard tor coinpleting the connection hetwcen said stations, a central station, means for normally connecting said central station to he irst called by a user, and means at said central station for connecting the signal circuit so that a selected station may then he called.

3. In a selective telephone system, a plurality of stations, means for connecting said stations in circuit including a signal circuit, an autcn'latic selecting` switchboard in said circuit 'tor completing the connection between said stations, a central station in said circuit normally connected to he called hy a user ot one et the other stations, manually operable means at said central station for connecting the signal circuit so that selected station inlay he` called directly by the user of one of n- En) llO disconnected from the other stations, and

manually operable means at the central station for opening that circuit to said central station and connecting the same to the called station, and means at the calling station or ringing the previously selected station directly by the user.

5. In a selective telephone system, a plurality of stations, means tor connecting said stations in circuit, a selecting` switchboard for completing the connection between said stations, a central station, a signal circuit normally closed thereto and open to the other stations, manually operable means at the central station tor opening that circuit to said central station and connecting the signal circuit so that any other previously selected station may be called by the user, and electrical means for maintaining the circuit closed during each talking period.

6. In a selective telephone system, a plurality of stations, including a central station normally connected to be called from any other ot said stations, means at each station for completing a signal circuit therefrom, and manually operable means at the central station for breaking the signal circuit and connecting it in the signal circuit of a previously selected station.

7. In a selective telephone system, a plurality of stations, including a central station normally connected to be called from any other of said stations, means at each station for completing a signal circuit therefrom, and manually operable means at the central station for breaking the signal circuit thereto and connecting it in the signal circuit of a` previously selected station` and electrical means for maintaining this circuit closed during each talking period.

8. In a. selective telephone system having a plurality of stations, a central station, means at the calling station for selecting the signal circuit of called stations, means interposed in said signal circuit between the dif- Vferent stations by which the signal circuit ot the central station is normally connected with the calling stations, and manually Operable means iior connecting the signal circuit ot the calling` and called stations and disconnecting the signal circuit to the central station.

9. In a selective telephone system having a plurality ot stations, manually operable means at each stat-ion for operating a selector to connect the talking and signalling circuits of the calling and called stations and switch means interposed in the selected signal circuit to disconnect that circuit and to normally connect the calling station in the signal circuit with a cent-ral station, and manually operable means to operate said switch means to connect said selected signal circuit and disconnect the signal circuit of said central station.

10. In a selective telephone system, a plurality of stations including a central station, each station having a transmitter, a receiver, a signal device and station-selecting mechanism, a signal switch at each station, said central station being normally connected to be signalled from all other stations, and a manually-operable switch at the central station for simultaneously disconnecting that station signal irom all other stations and connecting the calling station to its selected station.

11. In a selective telephone system, a plurality of stations including a central station, a selectiveI switchboard, a station controlled automatic selector, a. manually-controlled switch normally connected to complete the signal circuit through said switchboard from the selecting station to the central station only and responsive to manual manipulation to disconnect the signal circuit from said centralstation and connect it to the signal circuit of said selected station through ,said switch and said automatic selector.

12. In a selective telephone system having a plurality of stations connected through a selecting switchboard, a central station, means operable at the calling station for selecting the signal circuit of the called station, switch means interposed in the selected signal circuit for normally opening that circuit and closing the signal circuit ot the central station, electro magnetic means for holding said switch means to close the selected signal circuit and open the central signal circuit, and manually operable means for closing said selected signal circuit and operating said electro magnetic means.

13. In a selective telephone system having a plurality of stations connected in the circuit including a central station, means in the system whereby the central station is first called by the usci', a portable desk instrument at the central station, and means carried by said instrument responsive to a manual operation for connecting the signal circuit so that a selected station may be called directly by the user from the calling station.

14. In a selective telephone system having a plurality of stations connected in the circuit including a central station, means in the system whereby the central station is iirst called by the user, a portable desk instrument at the central station having a removable base member, and means carried in said base member responsive to manual operation for connecting the signal circuit so that a selected station may be called directly by the user.

15. In a selective telephone system having a plurality ot' stations including a central staion connected through an automatic selectine switchboard, a portable desk instrument in the system at the central station, a base member carried by said instrument, and controlling means carried by said base member by which the signal circuit to central may be opened and connection made whereby the seleeted'station may be called directly by the user.

16. In a selective telephone system having a plurality of stations including a central station connected through an automatic selecting switchboard, a portableV desk instrument in the system at the central station, a

f base member carried by said instrument, controlling means carried by said base member by which the signal circuit to central may be opened and connection made whereby the selected station may be called directly by the user, and means in said controlling means whereby said connection may be automatically broken at the end of each talking period. 17. In a selective telephone system having e. plurality of stations including a central station connected through an automatic selecting switchboard, a portable desk instrument in the system at the central station, a base member carried by said instrument, and controlling means carried by said base member by which the signal circuitto central may be opened and connection made whereby the select-ed station may be called directly by the user, and manually operable means in said controlling means, whereby said connection may be prolonged for any desired period.

In testimony whereof I aliix my signature.

JOHN F. CAVANA GH. 

